There has been a tremendous amount of work since the release of v1.4 and we are now very pleased to present you the first v1.5 release candidate. We're moving along quite nicely towards LuxRender v2.0 and we hope you'll enjoy that new release.As for v1.4, LuxRender itself has not seen much changes but the new LuxCore rendering core has gained a lot of features and nearly matches classic LuxRender.You can get a visual outlook of the new features in the wiki: major speed improvements, volume precedence, new materials and textures, volume emission, strands, better integration in Blender and 3DSMax to name just a few.Paolo, Reality plugin author, has experimented more than 10x speed improvements with the new rendering modes: https://www.youtube.com/watch?v=b6fyJQOzfvU

SATtva wrote:Don't you have this option under Volume parameters section? If not, make sure you've updated LuxBlend correctly.

Nope, no sign of that. After I installed Luxrender I completely removed my old LuxBlend folder from Blender before copying the new one from the LuxRender folder. I noticed that in LuxCore mode the material preview isn't working as well.